Environmental licence monitoring

The reports are usually published on the website within 14 working days of all the results being available, but some analyses can take days or weeks to complete. For example, a BOD analysis takes five days to complete and some pesticide analyses may need to be sent to different laboratories.

Where required, data is standardised so that results are expressed according to the conditions of the relevant licence.

Monthly summary reports are stored on the website for up to four years.

The 50 percentile and 90 percentile results are determined at the end of the 12-month licence period. These results are reported in the yearly summary reports for each plant and to the EPA in the Licence Annual Return. The 100 percentile limit is applicable to all monitoring results and, when specified in the licence, is reported in the monthly summary reports.

A Three Day Geometric Mean (3DGM) test is a way to average a set of values and is commonly used with water quality assessments which show a great deal of variability. 3DGM is calculated by multiplying the results of the analysis of three samples collected on three consecutive days and then taking the cubed root of that amount (3DGM result = cube root of D1 result x D2 result x D3 result). We have three licences which specifies 3DGM limits ie our three ocean outfalls – Burwood, Boulder Bay and Belmont. If we exceed certain 90 percentile limits then the licence requires us to perform a 3DGM test. Currently, we rarely exceed the 90%ile limit and thus it is very unusual for us needing to carry out 3DGM tests.